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Performance & Optimization

Practical guides to speed up your sites and apps and pass Core Web Vitals.

Performance & Optimization

Code Splitting Guide 2026: Faster Loads with Dynamic Imports

How to split your JavaScript so users download only what they need — route-based splitting, dynamic import(), React.lazy, vendor chunks, prefetching and handling stale-deploy chunk errors — each with why and a code example.

· 7 min read
Performance & Optimization

How to Optimize CSS in 2026: 14 Techniques for Fast Styles

Practical CSS performance techniques — remove unused CSS, inline critical styles, GPU-composited animation, content-visibility, containment and font optimization — each with why it matters and a code example.

· 7 min read
Performance & Optimization

How to Optimize React Performance in 2026: 14 Techniques

Practical React performance techniques — the React Compiler, stable keys, list virtualization, useTransition/useDeferredValue, code splitting, Server Components and streaming SSR — each with why it matters and a code example.

· 8 min read
Performance & Optimization

How to Reduce JavaScript Bundle Size in 2026: 14 Ways

Cut your JavaScript bundle — measure with an analyzer, code-split by route, tree-shake, replace heavy dependencies, enable Brotli, set a realistic browserslist and enforce a budget in CI — each with why and a code example.

· 6 min read
Performance & Optimization

How to Speed Up JavaScript in 2026: 16 Performance Techniques

Make JavaScript fast — break up long tasks with scheduler.yield(), offload to Web Workers, avoid layout thrashing, debounce, use passive listeners and the right data structures — each with why it matters and a code example.

· 8 min read
Performance & Optimization

Image Optimization Guide 2026: Faster Images, Better LCP

A complete guide to optimizing images — modern formats (AVIF/WebP), responsive srcset, preventing CLS, lazy loading vs the LCP image, compression, CDNs and placeholders — each with why and a code example.

· 6 min read
Performance & Optimization

How to Improve Core Web Vitals in 2026: LCP, INP & CLS

A practical guide to the three Core Web Vitals — what LCP, INP and CLS measure, the exact 2026 thresholds, and how to fix each one — with the reasoning and code for every technique.

· 7 min read
Performance & Optimization

Lazy Loading Best Practices 2026: Images, Components & Routes

How to lazy-load the right way — native image/iframe lazy loading, never deferring the LCP image, route and component splitting, IntersectionObserver, prefetch-on-intent and handling chunk errors — each with why and a code example.

· 6 min read
Performance & Optimization

Modern Web Performance Checklist 2026: 37 Wins

A complete, up-to-date web performance checklist for 2026 — measurement, loading and delivery, JavaScript, CSS, images and fonts, Core Web Vitals, caching and monitoring — 37 concrete, verified items grouped so you can work top to bottom.

· 4 min read
Performance & Optimization

Tree Shaking Guide 2026: Eliminate Dead Code from Bundles

How tree shaking works and how to make it actually work — ES modules, the sideEffects flag (and its CSS gotcha), avoiding barrel files, pure annotations and verifying with an analyzer — each with why and a code example.

· 7 min read

Performance is a feature users feel before they can name it — the difference between an app that responds and one that hesitates. This category is about making the web fast in the ways that matter: quicker loads, smoother interaction, and passing Core Web Vitals, the metrics Google uses to measure real-world experience.

The approach is measure-first. Guessing at bottlenecks wastes effort on the wrong thing; the guides here show how to profile, read the numbers, and target the change that moves them. Small techniques can be tried directly in the editor, where the live preview makes a rendering or layout cost visible immediately.

Coverage runs from the fundamentals — LCP, CLS and INP, bundle size, lazy loading and caching — to framework-specific wins in React and modern build tools. The goal is durable speed: habits that keep a site fast as it grows, not a one-off tune-up that regresses next sprint.

Frequently asked questions

What are Core Web Vitals?
Three metrics Google uses to score real user experience: LCP (how fast the main content loads), CLS (how much the layout shifts unexpectedly) and INP (how quickly the page responds to input). They affect both usability and search ranking, so they are worth optimising directly.
How do I measure my site's performance?
Start with Lighthouse in Chrome DevTools for a lab snapshot, then use field data from the Chrome UX Report or Search Console for what real users experience. Measure before and after every change so you know it actually helped.
What usually has the biggest impact?
For most sites, reducing JavaScript. Shipping less script, splitting bundles and deferring non-critical code improves load and interactivity more than almost anything else. Right-sizing images and adding caching are the next-biggest, lowest-effort wins.
Does performance really affect SEO?
Yes. Core Web Vitals are a ranking signal, and slow pages lose users regardless of ranking — bounce rate climbs with every extra second. Fast pages tend to rank better and convert better, so the effort compounds.
Can I test performance techniques on XCODX?
You can prototype and compare approaches in the editor with its live preview, which is ideal for isolating a rendering or layout-shift issue. For full field metrics you will still measure on your deployed site, but the technique itself is quick to validate here.